Cartridge type brush holder

ABSTRACT

A brush unit for use in a micromotor used in a dental instrument which comprises a support disk and a pair of brushes mounted on said support disk so that said brushes are held in contact with the commutator. The support disk and the brushes form a cartridge which can be detachably attached to said micromotor.

United States Patent 119 1111 3,851,197 Watanabe Nov. 26, 1974 CARTRIDGETYPE BRUSH HOLDER 2.753.477 6/1956 Yahn 310/244 2,755.399 7 I956 Ph'll'3l0/244 [75] Invenm" Ymhmk' wannabe Kyoto, Japan 2,760,094 8/1956 Ed mrridson 310/244 73 Assignee: Kabushiki Kaisha Morita 3 :1 UC lSelsakusho Kyoto Japan 3,648,086 3/1972 Renner 310/227 [22] Filed: Nov.2, 1972 3,654,504 4/1972 Susdorf 0. 310/239 [2]] Appl. No.: 303,127

Primary ExaminerR. Skudy Attorne A em, or Firm-Christenson, OConnor,Foreign Apphcatlon Prlorlty Data Garrisoi; &gHavelka Nov. 9, 1971 Japan46404807 [52] U.S. Cl 310/ MM, 310/91, 310/244 [57] ABSTRACT [51] Int.Cl. H02k H02k 5/00 [58] Field of Search 310/40 MM, 241 51 244 brush usemcrommor 5 a 310/245 227 239 240 233 1 lnstrument wh1ch compnses asupport d1sk and a pan d of brushes mounted on said support disk so thatsaid brushes are held in contact with the commutator. The [56]References Cited support disk and the brushes form a cartridge whichUNITED STATES PATENTS can be detachably attached to said micromotor.

2.325915 8/1943 5 Claims, 2 Drawing Figures Naul 310/40 MM CARTRIDGETYPE BRUSH HOLDER This invention relates to a micromotor for use in adental handpiece and more particularly to a brush used in themicromotor.

A dental handpiece is provided at its outer end with a detachable toolfor cutting or drilling, which is rotated at a high speed when used fordental treatment. The handpiece contains a micromotor therein forrotating the tool. This micromotor is a direct current motor so that ithas a commutator and brushes. The brushes are likely to be worn with useand must be exchanged for new ones every now and then. The dentist whouses such dental handpieces is not always an expert in electricalinstruments so that he finds it somewhat difficult to exchange brushesin the motor of his handpiece. As the brushes become worn, graphitewhich is the material constituting them is ground into power, which isaccumulated in the handpiece to deteriorate the working efficiency ofthe instrument. Therefore, the motor must sometimes be decomposed forcleaning by removing the accumulated powder therefrom, after which thecomponent parts must again be assembled into the motor. The workrequires considerable skill and time.

Accordingly it is'one object of the invention to simplify work forexchange of brushes in micromotors for use in medical instruments.

Another object of the invention is to make it easy to remove from insidethe motor graphite powder worn off from the brushes.

The invention will be described in detail with reference to theaccompanying drawings, wherein:

FIG. I is a longitudinal cross-section of one embodiment of theinvention; and

FIG. 2 is a perspective view, on an enlarged scale, of the principalportion of the device shown in FIG. 1.

Referring now in detail to the drawings, there is shown a micromotorgenerally designated by l. The motor is enclosed inside a handpiece, notshown, and secured to a suitable place therein. The motor comprises afield pole 2 made of a permanent magnet, an armature 3, an armaturewinding 4 and a shaft 5 journaled in an axially spaced pair of radialbearings 6 and 7. The leads connected to the armature winding 4 arepassed through bores in a guide sleeve 8 to be connected to a commutator9. A tool (not shown) to be rotated is connected to the left-hand side,as viewd in FIG. 1, of the shaft 5.

A brush unit 10 comprises a support disk 11 on which a pair of brushholder pins 12 are fixed and spaced apart diametrically of the disk.Each of the pins 12 pierces loosely through a sleeve 13 which can freelyrotate about the pin and to which a brush holder 14 has its one endsecured. The holder 14 is provided at its outer end with a brush'lS, anda coil spring 16 encircling the sleeve 13 urgesthe holder 14 to turnabout the pin 12 in such a direction as to press the brush against thecommutator 9. A cap 17 is detachably attached to the disk to cover thebrushes and other component parts thereon. The pins 12 are connected toa source of electricity, not shown.

The disk 11 with the cap 17 attached thereto can be put into or takenout of the motor casing like a car tridge.

When the brushes are worn and must be replaced by new brushes, the disk11 with the cap 17 thereon is simply taken out from inside the motorcasing, and a new brush unit 10 enclosing new brushes 15 is put into thecasing. This is a very simply manual work.

The graphite powder produced by wear of the brushes has flown off due tocentrifugal force to be attached to the inner surface of the cap andseldom flies out of the cap into that part of the motor casing where thearmature is enclosed. Therefore, when the brush unit is taken out, thepowder attached to the cap is also taken out. Then, the cap may be takenoff from the disk 11 to brush off the attached powder.

Since the dental handpiece is used in the mouth of a patient to cut ordrill the teeth, reduction of the insulation resistance of theinstrument would result in leakage of electric current to the dentalnerves which would incur a great danger to the patients life. The deviceof the invention can completely eliminate such a danger.

Thus, in accordance with the invention, a simple manual work sufficesfor replacement of worn brushes for new ones in a micromotor used in adental handpiece, and simultaneously with the replacement the graphitepowder produced by the wear of the brushes can be removed from insidethe motor.

What I claim is:

l. A brush holder cartridge for use in a micromotor, wherein themicromotor includes a casing having inner and outer surfaces, the brushholder cartridge comprising:

a support member;

a pair of brush holders secured to said support member, said pair ofbrush holders operative to hold a pair of brushes positioned therein incontact with a commutator of said micromotor; and cartridge cap, whichcartridge cap engages said support member such that said support memberand said cartridge cap substantially enclose said brush holders andbrushes about said commutator, said cartridge cap being held inengagement with said support member by frictional contact between saidcartridge cap and the inner surface of the micromotor casing when saidbrush holder cartridge is operatively positioned in said micromotor.

2. An apparatus of claim 1, wherein said support member has definedtherein a notch around the periphery thereof, said notch receiving aportion of said cartridge cap, said support member and said cartridgecap thereby engaging one another, and wherein said cartridge cap isconcentric with the inner surface of the casing.

3. A brush holder cartridge for use in a micromotor, wherein themicromotor includes a casing having inner and outer surfaces, the brushholder cartridge comprising:

a support member;

a pair of brush holders secured to said support member, said pair ofbrush holders operative to hold a pair of brushes positioned therein incontact with a commutator of said micromotor; and

a cartridge cap, which cartridge cap engages said support member suchthat said support member and said cartridge cap substantially enclosesaid brush holders and said brushes about said commutator, said supportmember including a pair of spaced electrically conductive pins integralat one end thereof with said support member, said conductive pinsextending from said micromotor such that electrical energy may beapplied thereto when '1 brush holder.

of brush holders has associated therewith a spring for maintaining saidbrushes in contact with the commutator, each spring having two opposingends and being positioned over a sleeve, one end of each spring beingrigidly connected to said support member, the other end thereof beingrigidly connected to its associated

1. A brush holder cartridge for use in a micromotor, wherein themicromotor includes a casing having inner and outer surfaces, the brushholder cartridge comprising: a support member; a pair of brush holderssecured to said support member, said pair of brush holders operative tohold a pair of brushes positioned therein in contact with a commutatorof said micromotor; and a cartridge cap, which cartridge cap engagessaid support member such that said support member and said cartridge capsubstantially enclose said brush holders and brushes about saidcommutator, said cartridge cap being held in engagement with saidsupport member by frictional contact between said cartridge cap and theinner surface of the micromotor casing when said brush holder cartridgeis operatively positioned in said micromotor.
 2. An apparatus of claim1, wherein said support member has defined therein a notch around theperiphery thereof, said notch receiving a portion of said cartridge cap,said support member and said cartridge cap thereby engaging one another,and wherein said cartridge cap is concentric with the inner surface ofthe casing.
 3. A brush holder cartridge for use in a micromotor, whereinthe micromotor includes a casing having inner and outer surfaces, thebrush holder cartridge comprising: a support member; a pair of brushholders secured to said support member, said pair of brush holdersoperative to hold a pair of brushes positioned therein in contact with acommutator of said micromotor; and a cartridge cap, which cartridge capengages said support member such that said support member and saidcartridge cap substantially enclose said brush holders and said brushesabout said commutator, said support member including a pair of spacedelectrically conductive pins integral at one end thereof with saidsupport member, said conductive pins extending from said micromotor suchthat electrical energy may be applied thereto when said support memberis operatively positioned in said micromotor.
 4. An apparatus of claim3, including a pair of sleeves, each sleeve being positioned around anelectrically conductive pin and being rotatable thereabout, each sleevehaving a brush holder fixedly secured thereto.
 5. An apparatus of claim4, wherein each of said pair of brush holders has associated therewith aspring for maintaining said brushes in contact with the commutator, eachspring having two opposing ends and being positioned over a sleeve, oneend of eaCh spring being rigidly connected to said support member, theother end thereof being rigidly connected to its associated brushholder.